Double acting rotary compressor



DOUBLE ACTING ROTARY COMPRESSOR Filed Jan. 21, 1959 3 Sheets-Sheet 1 INVENTOR GROVE/P 0. FRASER H I 8 AT TO R N E Y June 27, 1961 G. D. FRASER 2,990,109

DOUBLE ACTING ROTARY COMPRESSOR Filed Jan. 21, 1959 3 Sheets-Sheet 2 I9 Io I2 5 49 |e l4 ZL/ %L771 5\ I? IO 50 INVENTOR GROVER D. FRASER I4 I? HIS ATTORNEY June 27, 1961 c. D. FRASER 2,990,109

I R j I] INVENTOR W GROVER 0. FRASER 3? BY F/6.6 ms ATTORNEY United States Patent soll-Rand Com an N k of New ersey P y, ew Yor NY, a corporation Filed Jan. 21, 1959, Ser. No. 788,135 3 Claims. (Cl. 230-158) This invention relates to compressors and it has for its ob ect to provide a novel and improved double-acting compressor of the rotary type.

Another object of the invention is to increase the capacity of a compressor of the above type and thus obtain a greater output with a smaller machine than has heretofore been possible.

Still another object is to provide a simple and efiicient two-stage compressor of minimum overall size employing a single rotor.

Various other objects and advantages will be apparent as the nature of the invention is more fully'disclosed. The compressor disclosed herein for the purpose of illustrating the invention comprises a compact casing having a generally elliptical interior chamber containing a tubular rotor driven by a suitable source of power. The casing has a cover plate containing a generally elliptical stator which extends within the tubular rotor. The result of this construction is that two diametrically opposed crescent-shaped chambers are formed between the outer tubular surface of the rotor and the elliptical wall of the casing chamber, forming one compressor stage; and two smaller diametrically opposed crescentshaped chambers are formed between the ellipticalsurface of the stator and the inner tubular surface of the rotor, constituting the second compressor stage.

The tubular rotor has a plurality of equally spaced vane slots containing vanes which are slidable in said slots and make contact at all times with the elliptical surface of the stator and the elliptical wall of the casing chamber. Additional novel features of the invention, hereinafter more fully described, include the construction and arrangement of the vanes carried by the rotor, and the various combinations of elements including in particular the intake and discharge passages in the cover plate cooperating with the different compressor chambers.

The invention will be described in detail in connection with a preferred embodiment illustrated in the accompanying drawing, in which:

FIG. 1 is a vertical sectional view through a two stage, two stroke rotary compressor embodying the invention;

FIG. 2 is a transverse section taken on line 2-2 of FIG. 1;

FIG. 3 is a transverse section taken on line 33 of FIG. 1;

FIG. 4 is an enlarged fragmentary sectional view of the rotor and slidable vanes, showing typical vane positions;

FIG. 5 is a detail section through one of the intake ports of the compressor, taken on line 55 of FIG. 3; and

FIG. 6 is a detail section through the second stage intake porting, taken on line 66 of FIG. 3.

The compressor shown in FIG. 1 comprises an outer casing 1 secured by bolts 2 to the casing of an electric motor 3.

The casing 1 has a roughly elliptical interior chamber 4 in which is rotated a tubular-shaped rotor 5. The rotor 5 is integral with, or secured to, a hub 6 which is splined on the shaft 7 of motor 3 and makes a close running fit with the wall bushing 11 of easing 1.

At the opposite end of the casing 1 (to the left in FIG. 1) a cover plate 9 is secured to said casing by bolts H 2,990,109 Fatented June 27 iice 10. A suitable gasket 12 seals the joint between the casing and cover plate as shown in FIGS. 1 and 2.

A roughly elliptical stator 14 is secured to the inner face of cover plate 9 by bolts 15, and is positioned within the rotor 5, as best shown in FIGS. 2 and 3.

The major axes of chamber 4 and stator 14 are in alignment with the axis of rotor 5 so that two diametri cally opposed crescent-shaped chambers 16 and 17 are defined between the stator 14 and the inner cylindrical surface of tubular rotor 5; and two diametrically opposed crescent-shaped chambers 19 and 20 are formed between the outer cylindrical surface of rotor 5 and the elliptical wall of the chamber 4 in casing 1.' The chambers 16 and 17, and the chambers 19 and 20, are equally spaced around the stator 14 with respect to the symmetry lines of the chambers, i.e. diameters passing horizontally and vertically through FIG. 2.

FIGS. 1 and 3 show the interstage passages in the cover plate 9 of the compressor. There are two main axially aligned tubular passages 22 and 23, the outer ends of which are sealed by pipe plugs 24 and 25, respectively. There are two intake pipes 2'7 and two discharge pipes 28 connected to cover plate 9, though only one of each is shown in FIG. 1. One intake pipe opens into the bore 29 in cover plate 9 (FIGS. 1 and 3) while the other intake pipe (not shown) opens into the bore 30 in cover plate 9 (FIG. 3). Air entering one inlet pipe passes from the bore 29 through the connected duct 32. into the crescent-shaped chamber 20'. Air entering the other inlet pipe passes from the bore 31 through the connected duct 33 into the crescent-shaped chamber 19.

The crescent-shaped chamber 19 is connected to duct 35 in cover plate 9.' Duct 35' opens into the tubular passage 22-from which duct 36 leads into the arcuate duct 37 (FIG. 3) communicating with the crescentshaped chamberilfi. ,From said crescent-shaped chamber 16 air passes into duct 38, thence through bore 39 into discharge pipe 28.

The crescent-shaped chamber 20 is connected to duct 40 in cover plate 9. Said duct 40 opens into the tubular passage 23 from which duct 42 leads into the arcuate duct 43 (FIG. 3) communicating with the crescentshaped chamber 17. From said crescent-shaped chamber 17 air passes into duct 44 thence through bore 45 into the second discharge pipe.

The tubular rotor 5 has a plurality of elongated vane slots 47 extending radially therethrough for the reception of flat-faced elongated vanes 48 which are slidable therein. There are twelve equally spaced slots 47 as shown in FIGS. 2 and 3. The length of each vane 48 is equal to the distance from the periphery of the stator 14 to the periphery of the interior chamber 4 measured on a line radiating from the center of the stator; this distance being the same on. any such radial line so that the slidable vane stays in contact with the surfaces of both the stator 14 and the chamber 4 at all times to prevent leakage. The vanes are lubricated in any conventional manner, for example oil may be injected into the air for cooling the air and lubricating the compressor.

The vanes 48 are preferably split or laminated as shown in FIGS. 2, 3 and 4, and are held in frictional contact with the slots 47 so that the effect of centrifugal force on the vanes is reduced to a minimum. The two split halves or laminations of each vane 48 contain mating elongated transverse slots 49, and an elongated flexible spring of any suitable type is housed within each 5 pair of mating slots 49 of each complete vane, as best shown in FIG. 4. In the embodiment illustrated the springs 50 are elongated members of X-shaped crosssection which provide an eflfective seal between the laminations forming each vane. With such split springpressed vanes, an end of each vane part is held in contact 3 with the surface of the stator 14 or the surface of the chamber 4. The extremities of the vanes are rounded as shown in FIGS. 2, 3 and 4 to facilitate such contact.

In operation the vanes 48 are cammed outwardly by the rotation of rotor 5 to the outer limiting position prior to starting compression in chambers 19 and 20. Similarly, each vane is cammed inwardly to its innermost limiting position by the elliptical wall of chamber 4 before compression in the chambers 16 and 17 starts.

While a specific embodiment has been disclosed herein for purposes of illustration, it will be evident to those skilled in the art that the invention is capable of various modifications and adaptations within the scope of the appended claims.

The invention claimed is:

1. A two-stage rotary compressor comprising a casing, a generally elliptically-walled chamber in said casing, a tubular rotor operatively mounted in said chamber to form therewith a pair of diametrically opposed compression chambers, intake ports communicating with said compression chambers, a generally elliptical stator in said casing positioned within said tubular rotor coaxially with said rotor and casing and forming therewith a second pair of diametrically opposed compression chambers, passageway means for connecting said two pairs of compression chambers, discharge ports leading from said second pair of compression chambers, a plurality of equally spaced slots extending radially through said tubular rotor, and vanes slidably mounted in each of said slots, each of said vanes being composed of two flat-faced laminations, resilient means acting on the laminations of each vane to slide said vanes in said slots, each of said vanes having an outer edge engaging the elliptical wall of said first-mentioned chamber and an inner edge engaging said elliptical stator, said two laminations of each vane being rounded at the ends and containing mating elongated transverse slots, and in which an elongated spring is housed within each pair of said mating slots.

2. A twostage rotary compressor comprising a casing having a generally elliptical interior chamber, a tubular rotor operatively supported at one end of said chamber in said casing and forming therewith a pair of diametrically opposed crescent-shaped compression chambers, a removable cover plate closing the other end of said firstmentioned chamber, a generally elliptical stator carried by said cover plate and positioned within said tubular rotor coaxially therewith and with said casing and forming therewith a second pair of diametrically opposed compression chambers, a plurality of equally spaced slots extending radially through said tubular rotor, and vanes slidably mounted in each of said slots, resilient means for sliding said vanes in said slots each of said vanes having an outer edge engaging the elliptical interior of said first-mentioned chamber and an inner edge engaging said elliptical stator, said cover plate containing intake passages opening directly into said first mentioned pair of compression chambers, ducts connecting said first mentioned pair of compression chambers with said second pair of compression chambers, and discharge ducts directly connected to said second pair of compression chambers.

3. A two-stage rotary compressor according to claim 2, in which the laminations of each vane contain mating elongated transverse slots, and in which an elongated resilient member of X-shaped cross-section is seated in each pair of mating slots.

References Cited in the file of this patent UNITED STATES PATENTS 

